1. Field of the Invention
The present invention relates to a method and an apparatus for expanding bead portions of a green tire and sequentially inserting the upper and lower bead portions into bead rings of upper and lower metal molds before tire shaping is carried out in a tire vulcanizing machine.
2. Description of the Prior Art
The heretofore known apparatus consists of upper and lower metal molds disposed in a vulcanizing machine and adapted to move up and down relative to each other and a center mechanism disposed in the lower metal mold. When precisely centering a green tire with respect to bead ring portions of the upper and lower metal molds, the green tire is first transported to the metal molds by means of a . loader, and is then set at an upper metal mold bead ring portion or at a lower metal mold bead ring portion. With such an apparatus in the prior art, only an upper or lower bead portion of the green tire is set at the bead ring portion of the corresponding metal mold, and the remaining lower or upper bead portion of the green tire cannot be set precisely at the bead ring portion of the corresponding metal mold. In addition, if the green tire should have been deformed before it is transported by the loader, the green tire could not be set precisely at the metal mold bead ring portion, and the deformation would have an adverse effect on the uniformity of the vulcanized tire.
In the prior art, after a green tire is loaded in upper and lower molds of a tire vulcanizing machine, a shaping operation is carried out upon vulcanization of the tire. In the shaping operation, a bladder is pressed against the inside of the green tire under pressure, and the bead portions of the green tire are forcibly pushed into upper and lower bead rings of the metal molds by the bladder.
Therefore, there is a possibility that vulcanization of a tire may be carried out without the green tire bead portions being surely inserted into the bead rings of the metal molds.